stm8系列--可变频率PWM输出

 PA3 STM8S003F3

timer2_init();    //初始化

#define PUL_COUNT 4000  
void timer2_init(void)
{

  TIM2_DeInit();  
  
  TIM2_TimeBaseInit(TIM2_PRESCALER_8, PUL_COUNT-1); //62.5HZ   2M/8 /4000=62.5HZ 1个数4us   

  TIM2_OC3Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE, PUL_COUNT/2, TIM2_OCPOLARITY_HIGH);

  /* TIM1 counter enable */
  TIM2_Cmd(ENABLE);
}

#define ADD_LOAD  2000000/8

void set_pwm1(unsigned int  arr) //arr 设置的频率，单位HZ    占空比固定50%
{
double T_ARR;
unsigned int PWM_Per=0;

T_ARR=(double)ADD_LOAD/arr; 
T_ARR=T_ARR+0.5;
PWM_Per = (unsigned int)T_ARR;
TIM2_SetAutoreload(PWM_Per-1);
TIM2_SetCompare3(PWM_Per/2);    
}